1. Field of the Invention
The present invention relates to an electronic control device for controlling vehicular equipment, mounted on an automobile, for example.
2. Description of the Related Art
Until now, an electronic control device has been disclosed that includes a current detection resister and a short-circuit protection circuit for detecting a short (short circuit) of a load based on a voltage generated by a current flowing through the current detection resister, so as to protect a load drive unit against an overcurrent, wherein when a current flowing through a drive circuit including the load and a switching element is detected exceeding a predetermined value, the current flowing through the circuit is limited or shut off. (For example, refer to Patent Document 1.)    Patent Document 1: Japanese Laid-open Patent No. H3-106114
The conventional device disclosed in Patent Document 1, in order to limit or shut off the current flowing through the load drive unit when the current is detected exceeding a predetermined value, incorporates the current detection resister and the short-circuit protection circuit that detects the load short-circuiting, based on the voltage generated by the current flowing through the current detection resister, so as to protect the load drive unit against an overcurrent. However, the current detection resister needs to be connected in series with the load drive unit, and the resister not only wastes energy but also generates heat in itself, thereby leading to heating up the electronic control device as a whole. Moreover, in order to detect a large current, a resister having an appropriate power rating needs to be chosen, which in turn leads to an increase in the element size. Furthermore, when a short circuit is detected, the load drive unit needs to be held in a shut-off state; therefore, there has been a problem in that an extra latch circuit and the like need to be provided, leading to an increase in the circuit size.